Quantum transport in a mesoscopic ring: Evidence of an OR gate

We explore the OR gate response in a mesoscopic ring threaded by a magnetic flux ϕ. The ring is symmetrically attached to two semi-infinite one-dimensional metallic electrodes, and two gate voltages, Va and Vb, are applied in one arm of the ring; these are treated as the two inputs of the OR gate. All the calculations are based on the tight-binding model and the Green's function method, which numerically compute the conductance-energy and current-voltage characteristics as functions of the gate voltages, ring-to-electrode coupling strengths and magnetic flux. Our theoretical study shows that, for ϕ=ϕ0/2 (ϕ0=ch/e, the elementary flux-quantum), a high output current (1) (in the logical sense) appears if one or both the inputs to the gate are high (1), while if neither input is high (1), a low output current (0) appears. It clearly demonstrates the OR gate behavior, and this aspect may be utilized in designing an electronic logic gate.